In duplex reflective scanners capable of capturing an image from the front and rear of a document there is a camera and light source for each side. In this type of scanner the light source and camera aperture for one side are offset from the camera aperture for the other side so that the effects of light and thus image data bleeding through from the opposing side is minimized. Such a technique precludes scanning transparent documents since transparency scanning requires light being sourced from the side opposite from the charged coupled device (CCD) capturing the image.
U.S. Pat. No. 6,252,684 discloses one method of scanning transparencies in a simplex scanner. This method, however, relies on an additional lamp specifically for the purpose of transparency scanning. Much of the prior art enables transparency scanning on reflective simplex platen type scanners, for example see U.S. Pat. Nos. 5,381,245; 5,818,611; 5,822,087; 5,673,125; 5,677,777; and 5,726,790.